Prostat PRS-812 User manual

P R O F E S S I O N A L
S T A T I C
C O N T R O L
P R O D U C T S
Operations Manual
Resistance Meter
PRS-812

Copyright 2001-2009 by PROSTATCorporation. All rights reserved. Printed in the United States of
America. No part of this manual may be used or reproduced in any manner whatsoever without written
permission. For information contact PROSTAT Corporation, 1072 Tower Lane, Bensenville, IL 60106
PROSTAT is the registered trademark of PROSTATCorporation

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PRS-812 Resistance Meter
TABLE OF CONTENTS
PROSTAT®PRS-812 RESISTANCE METER
Title Page #
I. Introduction & Description .............................................................................................. 2
II. Cautions & Warnings....................................................................................................... 5
III. Controls, Connections & Indicators................................................................................. 7
IV. Setup & Calibration........................................................................................................ 13
V. Instrument Operation..................................................................................................... 15
VI. Instrument Maintenance................................................................................................. 29
VII. Warranty Information.......................................................................................................29
General Specifications................................................................................................... 31
Instrument Controls.........................................................................................................32

1
PRS-812 Resistance Meter
I. Introduction & Description
The PRS-812 Resistance Meter makes precision resistance
measurements from 0.1 up to 1.0x1012 ohms with an overall
measurement tolerance of 5%. It is capable of measuring up to
2.0x1014 ohms with tolerance depending on procedures and
conditions. The PRS-812’s wide range and close tolerance make it
the ideal ESD Auditing instrument for measuring resistance to a
variety of ESD and general industry specifications. It is operated
by programmed microprocessors that control the instrument’s
measurement process, resistance auto ranging, test voltage
selection, electrification periods, and display functions. It can be
operated in either fully automatic or manual modes, or a
combination of automatic and manual modes.
The PRS-812 is unique in that it records and stores up to 80
resistance measurements in its own non-volatile memory register.
Stored data is summarized with a push of a button.
Its accuracy is based on its ability to rapidly make several
measurements each second, and average them until a stable set of
eight measurements, all within 5% tolerance, are obtained. The final averaged data is displayed as
the resistance measurement. Typically, measurements at less than 1 ohm are within 5% of
tolerance, and those between 1.0 and 1.0x1012 ohms are within 0.5% of laboratory references.
While quite sophisticated in design, the PRS-812 Resistance Meter is easy to use and extremely
helpful in making accurate ESD auditing measurements, or general resistance and continuity
checks.
CAUTION
To avoid electrical shock or damage to the PRS-812 Resistance Meter, read this
manual completely before installing batteries or using the instrument
A. Measurement Applications
The PRS-812 Resistance Meter is designed to measure resistance characteristics of
electrostatic discharge (ESD) control materials and products to current ESD industry standards,
including:
Wrist Straps (ESD S1.1) Garments (ESD S2.1) Flooring (ESD S7.1)
Worksurfaces (ESD S4.1) Common Point ESD Grounds (ESD S6.1)
Footwear Seating Workstations
Equipment Carts Production Aids
Packaging (ESD S11.11, ESD S11.12 & ASTM 257) Material-Handling Containers
ESD Program Standard ANSI/ESD 20.20 & European Norm EN 00015
B. PROSTAT PRS-801 Resistance System Components:
The PROSTAT PRS-812 Resistance Meter includes the following items
1. PRS-812 Resistance Meter Instrument with 2 each 9V alkaline batteries
2. Two 10-foot leads (PRS-800 L) for general audit measurements up to 1.0x1012 ohms.
3. One heavy duty, black “Bulldog” clip (PRS-801 BC)
Figure 1: PRS-812 during Power Up

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PRS-812 Resistance Meter
4. Two Metal Alligator Clips (PSI-870-MAC)
5. One Insulated Test Plate (PRS-800-INS)
6. One Metal Test Plate (PRS-800-MTL)
7. One calibration shunt for low range adjustment (PRS-801 CC)
Optional accessories are available for the PROSTAT PRS-812 Resistance Meter. Refer to
PROSTAT’s current brochure or web site (www.prostatcorp.com) for additional information.
C. PRS-812 Basic Description & Functions
The PRS-812 Resistance Meter has several test, display and data logging functions:
The PRS-812 six basic measurement modes are described in the following table
MODE DISPLAYED
UNITS INDICATION RESIST.
RANGE TEST VOLTS TEST FUNCTIONS
AUTOMATIC 1 1.0EXX
IND - T
AUTO AUTO. AUTO. AUTOMATIC
RESISTANCE RANGE,
TEST VOLTS,
ELECTRIFICATION,
DISPLAY HOLD
AUTOMATIC 2 OHMS
- T
AUTO AUTO. AUTO. SEE TABLE NOTE #1
MANUAL 1 1.0EXX
IND - T
MANUAL MAN. MAN.
or
AUTO
TEST ONLY; NO
DISPLAY HOLD
UL= UNDER DECADE
LEVEL
MANUAL 2 OHMS
- T
MANUAL MAN. MAN.
or
AUTO
SEE TABLE NOTE #2
MANUAL/
AUTOMATIC 1
1.0EXX
IND - T
AUTO &
MANUAL MAN.
Start
AUTO
Run
AUTO.
MANUAL SETUP
STARTING DECADE,
AUTO ADJUST RANGE,
TEST VOLTS,
ELECTRIFICATION
DISPLAY HOLD
MANUAL/
AUTOMATIC 2
OHMS
- T
AUTO &
MANUAL MAN.
Start
AUTO
Run
AUTO.
TABLE NOTES:
#1 AUTOMATIC: RESISTANCE RANGES IN AUTO 0.1TO < 2.0E+12as follows
@<10V: 0.1 TO < 1.0E+04(0.1- < 10K)
@ 10V: 1.0E+04 TO < 1.0E+06(10K- < 1M)
@100V: 1.0E+06 TO < 2.0E+12(1M- < 2T) See Note Below
#2 MANUAL: RESISTANCE RANGES IN MAN 0.1TO < 2.0E+12as follows
@<10V: 0.1 TO < 1.0E+05(0.1- < 100K)
@ 10V: 1.0E+03 TO < 1.0E+09(1K- < 1G)
@100V: 2.0E+05 TO < 2.0E+12(200K-< 2T) See Note Below

PRS-812 Resistance Meter
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#3 AUTO-MANUAL: (Same as AUTOMATIC)
RESISTANCE RANGES IN AUTO-MANUAL 0.1TO < 2.0E+12as follows
@<10V: 0.1 TO < 1.0E+04(0.1- < 10K)
@ 10V: 1.0E+04 TO < 1.0E+06(10K- < 1M)
@100V: 1.0E+06 TO < 2.0E+12(1M- < 2T) See Note Below
NOTE: It is capable of measuring up to 2.0x1014 ohms with tolerance depending on procedures
and conditions.
2. The PRS-812 provides three separate test voltages for resistance measurements as
indicated in the table, above:
<10 Volts
10 Volts (Constant Test Voltage)
100 Volts (Constant Test Voltage)
In AUTOMATIC and AUTOMATIC/MANUAL modes, test voltages are selected by the
instrument based on resistance characteristics of materials being measured. In the
MANUAL mode the operator may select test voltage.
3. The PRS-812 displays resistance Measurements in several ways:
a. 14 individual operator programmable LED’s each representing one order of magnitude
from <103to >1012 ohms. The LED’s are preprogrammed for their respective colors
during final assembly of the instrument. Should a different color combination be desired
by the user, the program may be modified by PROSTAT during routine annual
calibration, or upon request. A modest service charge is required for this service. LED
colors include, GREEN, RED, YELLOW, and OFF (Blank)
b. The large Liquid Crystal Display (LCD) includes an analog (1 - 10) scale and X1, X10
and X100 multiplier indication for measurement in , K, M, Gand T.
c. Digital measurements are provided using integers and , K, M, G, Tindicators, or
in exponential format (1.0EXX) with -Tindicators.
4. The PRS-812 includes data logging (storage) capabilities for up to 80 data points when
RECORD is selected. The instrument will provide calculation and display of Minimum,
Maximum and Average of all measurements in the instrument’s memory at any time
RECALL is selected.
II. Cautions & Warnings
A. As with any electrical device, use proper safety precautions and safe measurement procedures
to avoid personnel shock and arc discharge.
B. The PRS-812 Resistance Meter is battery operated and delivers test voltages up to 100 volts.
NOTE: The PRS-812 provides very accurate measurements up to 1.0x1012 ohms,
and has the capability to display values up to 2.0x1014 ohms. However, the user
should be aware that accuracy degrades rapidly above 1.0x1012 ohms.

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PRS-812 Resistance Meter
CAUTION
To avoid electrical shock, do not touch lead conductors, fixtures or
accessories except as specifically instructed in this and PROSTAT
accessory operations manuals.
C. The instrument is current limited for safety, However, if improperly used it may be capable of
delivering an annoying shock to a person touching conductors energized by the PRS-812,
particularly at 100 volts.
D. Although the PRS-812 is current limited, a distinct hazard exists in the person’s reaction to a
potential shock.
E. To avoid personnel shock, follow the General Operations instructions at all times. Do not
touch energized electrodes or fixtures when power is applied except as specifically described
in this and accessory instructions.
F. Do not operate or store the instrument in damp environments or wet conditions.
CAUTION
Storage or use of this instrument in high humidity, damp or wet
conditions may cause damage to the instrument’s electronic circuits,
effect performance and can increase the possibility of personnel
shock or arc discharge.
G. Do not use the PRS-812 in combustible or explosive environments
WARNING
Improper handling and use of energized circuits may cause arc
discharge, which in turn may cause the ignition of combustible
materials or fumes. Do not use exposed energized circuits in
flammable areas.
H. Do not attempt to measure energized circuits with the PRS-812
I. Do not use the PRS-812 if it becomes damaged in any way
J. Only qualified instrument personnel should attempt to service or repair the PRS-812
K. Other Safety & Operating Considerations
1. This manual displays cautions and warnings alerting the user to hazardous operation and
servicing conditions. CAUTION or WARNING headings throughout this publication flag this
information, where appropriate. Follow all caution and warning instructions at all times.
2. The PRS-812 is a precision instrument and should be operated by experienced personnel
familiar with using and handling of devices containing power supplies.

PRS-812 Resistance Meter
5
3. The PRS-812 contains Electrostatic Discharge Sensitive (ESDS) components. Qualified
personnel should service it only at ESD Controlled workstations. Do not attempt to
dismantle the PRS-812 without PROSTAT’s authorization and expert supervision. The
instrument contains exceptionally clean circuits that are aligned and adjusted in a precise
manner for optimal operation and accurate performance. Unauthorized opening of the PRS-
812 housing will void the instrument’s warranty.
4. Read this manual in its entirety before installing batteries or using the PRS-812.
5. Do not drop or cause unnecessary mechanical shock to your PRS-812 instrument
6. Store the instrument in a clean, dry environment. Do not expose the instrument to wet,
extremely hot or cold conditions.
7. If the unit is stored in a cold environment, allow it to stabilize at room temperature before
powering up the unit. This will prevent damage due to condensation that may accumulate on
the instrument’s circuit boards.
III. Controls, Connections & Indicators
Before operating the PRS-812 instrument become familiar with each control and display function. A
thorough understanding of the instrument’s operation will make its use a pleasant experience,
enhance measurement accuracy, avoid mistakes and prolong the life of the instrument.
CAUTION
The PRS-812 Contains Electrostatic Discharge Sensitive (ESDS)
components and includes precision alignment of circuit elements. Only
ESD Qualified instrument repair personnel should perform service.
WARNING
Unauthorized opening of the PRS-812 case or dismantling in
any manner WILL VOID THE INSTRUMENT’S WARRANTY.

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PRS-812 Resistance Meter
123
45
6789
+
-
11
12
10
Figure 2: PRS-812 Controls & Display Indicators
PRS-812 Controls
[1] FUNCTION/ MODE Toggles through Six Operation Modes
(1) AUTO: (AUTOMATIC) displays data in exponential format 1.0EXX
NOTE: AUTO in exponential format, e.g., 1.3E05, is the Default
start up mode when the instrument is turned ON.
(2) AUTO: (AUTOMATIC) displays data in , K, M, Gand T
In AUTOMATIC the instrument controls resistance ranges, test voltage and electrification periods.
(3) MANUAL: displays data in exponential format 1.0EXX
(4) MANUAL: displays data in , K, M, Gand T
In MANUAL, the operator selects resistance range in single decade
increments. Test voltage may be selected by the operator, or allowed to
function automatically based on resistance range selected. The operator
determines electrification period in seconds (SEC) using the displayed
timer in the center of the LCD.
(5) AUTO-MANUAL: displays data in exponential format 1.0EXX
(6) AUTO-MANUAL: displays data in , K, M, Gand T
12
3
5
9
6
4
1
10
11
-+
7 8
2

PRS-812 Resistance Meter
7
In AUTO-MANUAL, the operator manually selects the initial resistance
range in decade increments. Once set, the PRS-801 starts the
measurement process from the preset resistance decade, rather than re-
zeroing itself for each measurement. This feature saves measurement
cycle time and extends battery life. In this mode the instrument
automatically controls test voltage, range and measurement electrification
period.
[2] RESISTANCE
RANGE SELECT. Two Triangular Arrow Buttons UP () and DOWN () select Resistance
Measurement Range in single orders of magnitude while in MANUAL or
AUTOMATIC/MANUAL modes
[3] TEST VOLTS Manual Selection of <10, 10 or 100 volts in MANUAL, selects initial test
voltage. MANUAL Test Voltage & Resistance Limits are as follows:
@<10V: 0.1 TO <1.0E+04(0.1-< 10K)
@ 10V: 1.0E+02 TO <1.0E+09(100-< 1G)
@100V: 1.0E+05 TO <2.0E+14(100K-< 2T) NOTE: Optimal
minimum measurement in MANUAL using 100 volts is 2.0E+05.
[4] RECORD/
RECALL If REC is not displayed in the lower left corner of the LCD, pressing
RECORD/RECALL once turns Memory Register ON [REC will then be
displayed in LCD]. If REC is ON and measurement data is stored in
memory, pressing RECORD/RECALL once will provide access to the
memory register. Pressing RECORD/RECALL successively will
calculate and sequentially display Minimum [MIN], Maximum [MAX] and
Average [AVG] of data stored in the Memory Register. If memory is ON
and register contains stored data pressing RECALL will provide the
following information:
First Press RECALL: Provides access to data in
Memory
NOTE: MEM XX Flashes in LCD indicating number of data points in the
register and the last measurement is displayed. Pressing DOWN ()and
UP ()displays other data points and their respective position in the
register is shown in the MEM XX section of the LCD.
Second Press RECALL: Displays MIN Data Point in Memory
Third Press RECALL: Displays MAX Data Point in Memory
Note: When displayed, OL [Over Level] indicates a
measurement greater than (>) 2.0x1014 ohms, which is beyond
the measurement capability of the PRS-812.
Fourth Press RECALL: Displays AVG of all Memory Data Points

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PRS-812 Resistance Meter
Note: OL [Over Level] measurements [>2.0x1014 ohms] are not
included in displayed average (AVG) calculation.
Fifth Press RECALL: Returns System to normal operations
Note: If in RECALL mode, pressing RESET will return the
instrument to normal measurement operations.
[5] CLEAR In normal operations CLEAR erases data in Memory Register, discards
most recent measurement, or turns the REC function OFF as follows:
a. When in any operation mode, and HOLD is not displayed,
pressing CLEAR will erase all data stored in Memory.
b. If a measurement is displayed in HOLD, prior to pressing
RESET button pushing CLEAR will discard that held value
and will not enter it into Memory. Other data in Memory
Register remains intact.
c. If reviewing data in the Memory Register while in the
RECALL mode, pressing CLEAR will discard the displayed
data point. Other data in Memory Register remains intact and
indexes down one space to replace the discarded data point.
d. When in any operation mode, and HOLD is not displayed,
pressing CLEAR will erase all data stored in the Memory
Register. Pressing OFF will disable the REC mode and the
instrument will be de-energized. When powered up again the
REC mode will remain disabled until RECORD/RECALL is
pressed once.
[7] ON/OFF Turns instrument ON for normal operations, performs functional &
Battery tests, turns instrument OFF.
[8] BATT. TEST Displays GOOD on LCD if battery provides acceptable voltage for
accurate measurements, or displays Lo if unacceptable and batteries
require replacement.
[9] RESET Saves measurement and prepares instrument for next test cycle, i.e.,
enters measurement into Memory Register if REC is ON, and clears
HOLD and the LCD display between measurements.
[10] TEST Begins measurement sequence in accordance with selected mode
Note: If RECALL is not pressed, a fifth time OOPS will be
displayed in the LCD when TEST is next pressed. To Clear
OOPS, press RESET. The instrument will return to normal
NOTE: The process of turning the REC function OFF will clear
the Memory Register of all stored data. Be sure that this is
indeed desirable before pressing the CLEAR button.

PRS-812 Resistance Meter
9
[11] BATTERY BUSS
CUT OFF Battery buss cut-off switch is used to isolate the main batteries from the
instrument’s circuit during battery change, instrument storage and
transport.
Display Elements
[11] Colored LED’s 14 LED’s across the top of the PRS-812 indicate measurement order of
magnitude in decades from <103to >1012 + ohms.
[12] PRS-812 Liquid Crystal Display Elements:
AUTO When ON Indicates instrument in AUTOMATIC mode
MANUAL When ON indicates instrument in MANUAL mode
When AUTO and MANUAL are ON, indicates instrument is in
AUTOMATIC/MANUAL mode.
Analog Scale
& X100 Indicator The one decade analog scale elements darken to indicate measurement
integer. X1, X10 or X100 darken to indicate the scale multiplier.
Combine the Analog indicators with , K, M, Gand Tsymbols to
obtain an analog measurement.
MEM 00 Provides the number of data points stored in the Memory Register when
REC is ON and instrument is RESET in preparation for a new
measurement. The Memory Register can store up to 80 data points.
00 SEC Display’s electrification period required for the measurement when in
TEST during AUTOMATIC and AUTOMATIC/MANUAL measurement
modes. In MANUAL, provides continuous measurement timing up to 99
seconds, then restarts at 0 seconds.
NOTE: The PRS-812 provides very accurate measurements up to 1.0x1012 ohms,
and has the capability to “indicate” values up to 2.0x1014 ohms. However, the user
should be aware that accuracy degrades rapidly above 1.0x1012 ohms.

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PRS-812 Resistance Meter
MIN Displayed when RECALL button is pushed first time while in REC mode.
Number displayed when MIN is indicated is the Minimum data value in
Memory Register.
MAX Displayed when RECALL button is pushed a second time (sequentially) in
REC mode. Number displayed when MAX is indicated is the Maximum
data value in Memory Register.
AVG Displayed when RECALL button is pushed the third time (sequentially) in
REC mode. Number displayed when AVG is indicated is the Average of all
data values in Memory Register that are less than 1.0x1014 ohms. (OL’s
are not included in averaging calculation.)
Note: Either the RECALL button must be depressed a fifth time or RESET
pressed to return the system to its operational, measurement mode.
REC Indicates that the Memory Register is ON and is Recording data each time
the RESET button is depressed after a TEST measurement.
Ohms: Indicates measurement between 0.1 and 999 ohms
KIndicates measurements from 1,000 (1.0x103) to 990,000 (9.9x105) ohms
MIndicates measurements from 1,000,000 (1.0x106) to 999,000,000
(9.9x108) ohms
GIndicates measurements from 1,000,000,000 (1.0x109) to
999,000,000,000 (9.9x1011) ohms
TIndicates measurements from 1,000,000,000,000 (1.0x1012) to
999,000,000,000,000 (9.9x1014) ohms
<100 V Indicates <10, 10 or 100 volts being applied as the test voltage.
HOLD Indicates measurement is complete at the end of a TEST cycle. Holds
data point in display until instrument is RESET or CLEAR is depressed.
Battery indication for low voltage
PRS-812 Connections
[+] Positive
Terminal Power terminal for supplying Test Voltage to fixture or material under test.
[-] Negative
Terminal Sensing Terminal for measurement of current (I) through fixture or material
under test.
Battery Compartment
Located in lower section of case, opposite LCD display. The compartment holds two 9V-transistor
batteries. Two screws secure the battery cover. Note: Use only Long Life Alkaline Batteries.
Remove batteries when instrument is not in use for long periods of time.

PRS-812 Resistance Meter
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Figure 3: Opening Battery Compartment. Figure 4: Install 2 each 9V Batteries
IV. Setup & Calibration
A. Battery Installation (See Figures 3 & 4)
1. Position Battery Buss Cut Off switch to OFF position
2. To install batteries, remove two Phillips locking screws and cover. Attach two Long Life
Alkaline 9V batteries to the two battery buss connections provided.
3. Position batteries in compartment with power leads neatly positioned above battery
connections. Carefully re-install battery cover and locking screws.
NOTE: Do Not depress Red ON/OFF button during battery installation while Battery Buss Cut Off is
ON. Always switch Battery Buss Cut Off to OFF when changing batteries. Should the ON/OFF button be
depressed during battery change and Battery Bus is ON the instrument may lock up and not function
properly. In this case, simply disconnect the batteries, then re-install with Battery Buss switch in the OFF
position.
B. Low Resistance Range (<10 Ohms) Calibration
1. Install the calibration shunt across the Negative (-) and Positive (+) Lead Terminals (Figure
5, below).
Cover
Screws
Battery
Buss
OFF
Position
Leads
Neatly

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PRS-812 Resistance Meter
2. Press the Red ON/OFF power button. The instrument display should become energized, each
LED will be tested in sequence, and Good will is displayed in the LCD if the batteries have
sufficient test capacity.
3. Allow the instrument circuits to warm-up for a few minutes;
approximately 2 - 3 minutes are sufficient, prior to completing the
calibration sequence.
4. Press the Yellow RESET, then the Gray CLEAR button within ½
second. The message CAL will be displayed in the LCD. (See
Figure 6)
5. Press the Yellow RESET button to complete low range (0.1 to 10
ohm) calibration. The CAL message will automatically be cleared
when RESET is pressed. (See Figure 7)
6. Press the Green TEST button. Indicated resistance should be
1.02 (0.02) ohms as shown in Figure 7. Press RESET to clear
the display. NOTE: If 1.02 (0.02) ohms is not displayed, repeat
the calibration process.
7. Remove the calibration shunt from the lead terminals
8. The PRS-812 is now ready for wide range measurements from
0.1 to 1.0E+12 Ohms
Figure 6: Start the Calibration Sequence
by Pressing RESET then CLEAR within ½
Second
Figure 5: Low Resistance Range Calibration Shunt Installation.
Low Resistance Calibration Shunt
Installed in PRS-812 Terminals
PRS-812 Low Calibration Shunt
Calibration Reference
Resister
1
2

PRS-812 Resistance Meter
13
Figure 7: Complete Calibration Sequence by Pressing RESET. To confirm Calibration,
Press TEST to measure the Calibration Shunt resistance. Shunt resistance should display
1.02 Ohms 0.02 Ohms
V. Instrument Operation
A. Overview of PRS-812 Operation & Measurement Test Cycle Sequence
The following 10 points provide an overview for calibrating and using the PRS-812 for
resistance measurements.
1. Slide Battery Buss Cut Off switch to ON
2. Press Red ON/Off button once to power up PRS-812
a. Instrument performs circuit check, and tests LED’s, LCD display, and battery
voltage.
b. LCD displays Good if battery voltage suitable for instrument operation; displays Lo
if batteries require replacement
c. Instrument ends startup sequence in default AUTO, Exponential Display Mode
1.0EXX.
3. Select Function Mode if other than AUTO, Exponential Display Mode 1.0EXX is desired
by pressing MODE button.
4. Perform low resistance range calibration after 3 minute instrument warm-up, if desired
a. Install Calibration Shunt between positive (+) and negative (-) terminals
b. Press RESET then CLEAR within ½ second
c. CAL is displayed in LCD

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PRS-812 Resistance Meter
d. Press RESET to calibrate instrument to shunt reference
e. Press TEST to measure shunt resistance of 1.02 0.02 ohms ()
f. Press RESET button to prepare instrument for the next measurement
g. Repeat calibration procedure if necessary
h. Remove Calibration Shunt
5. Connect test leads to positive (+) [Power] and negative (-) [Sensing] terminals
Standard 10-foot test leads are used for general audit measurements.
6. Connect test leads to electrodes, fixture or circuit to be measured
7. Press Green TEST button to initiate Automatic measurement Test Cycle
a. The resistance range is reset to minimum. It is automatically adjusted in conjunction
with the resistance characteristics of the materials under test, based on:
(1) Test voltage; and,
(2) Current flow.
b. Test Voltage is reset to <10V and automatically increased in accordance with the
following material resistance characteristics:
(1) <10 Volts: 0.1 to less than 1.0x104 ohms (0.1- <10K)
(2) 10 Volts: 1.0x104 to less than1.0x106ohms (10K- < 1M)
(3) 100Volts: 1.0x106to 2.0x1014 ohms (1M- 200T)
c. Electrification period, i.e., the time period during which test voltage is applied to the
material under test, is automatically adjusted to the PRS-812’s measurement
characteristics and industry standards (ESD S11.11) as follows:
(1) 2 to 3 Seconds: 0.1 to less than 1.0x104 ohms (0.1- <10K)
(2) 2 to 4 Seconds: 1.0x104 to less than1.0x106ohms (10K- < 1M)
(3) 7 to 8 Seconds: 1.0x106to >1.0x1012 ohms (1M->1T)
(4) 15+ Seconds: 1.0x1012 to 2.0x1014 ohms (1T- 200T)
8. When the PRS-812 displays and holds the final resistance measurement, HOLD is
indicated in the lower, right corner of the LCD.
NOTE: The PRS-812 provides very accurate measurements up to 1.0x1012 ohms, and has the
capability to display values up to 2.0x1014 ohms. However, the user should be aware that
accuracy degrades rapidly above 1.0x1012 ohms.

PRS-812 Resistance Meter
15
9. To save the displayed measurement in the Memory Register and prepare the PRS-812
for the next measurement, press the Yellow RESET button. Pressing RESET causes
three functions:
a. Enters (saves) last measurement into Memory Register
b. Increases LCD displayed number of data points in the Memory Register (MEM) by
one, e.g., MEM 02
c. Returns the PRS-812 to its last function mode in preparation for the next
measurement
10. To make several measurements, simply press TEST to obtain the next measurement,
then RESET to save it. Repeat the TEST and RESET process for each measurement
desired.
Good Measurement Practices, specific Operational Procedures and descriptions of functional
modes are covered in detail, below.
The PRS-812 is processor controlled to obtain hundreds of measurements per second, and to make rapid
adjustments in resistance range and test voltage as necessary. It will display the resistance measurement of
the material under test based on the following criteria:
a. A digital numeric display is the averaged result of eight (8) individual, consecutive measurements,
each within 5% of each other
b. The display is continuously updated during the measurement’s electrification period
c. The final displayed measurement is the averaged result of the last eight (8) individual, consecutive
measurements, each within 5%, at the end of the electrification period.
d. If the material or test conditions vary such that eight consecutive measurements, each within 5% of
each other cannot be obtained, the PRS-812 will extend the electrification period until the
measurement criteria are met; or,
e. The electrification period will automatically be terminated and the most recent averaged result of
eight (8) individual, consecutive measurements will be displayed and held.
f. In rare cases, when a stable measurement cannot be obtained the display will reset. NOTE: When
several “held” measurements vary greater than 15 to 20 percent of each other this typically indicates
inconsistencies in the material or test conditions.
NOTE: REC must be displayed in the lower, left corner of the LCD in order
to enter the measurement in the Memory Register. If REC is not displayed,
p
ress RECORD/RECALL once, then
p
ress RESET to save the data.
NOTE: Be sure to press RESET after your last measurement to save it in your
Memory Register before turning the PRS-812 OFF. If the instrument is turned
OFF before pressing RESET the last measurement will be lost.

16
PRS-812 Resistance Meter
B. Good Measurement Practices
Several factors will effect precision resistance measurements. Most practitioners are aware
of the importance of using care when handling instruments, proper use of connections, lead
resistance, grounding, and the impact of electrical or electrostatic fields on their equipment.
As with most very precise instruments, the PRS-812 circuits and its cables are sensitive to
the effects of electromagnetic and electrostatic fields. These effects, are minimized by
instrument and test lead design and material selection. However, good measurement
practices should be exercised at all times to ensure accuracy and repeatability. Follow the
recommendations below to obtain optimal performance from the PRS-812.
1. Instrument handling and preparation
a. Do not drop or cause mechanical shock to your instrument
b. Store the instrument in a clean, dry environment. Do not expose the instrument to
wet, extremely hot or cold conditions.
c. If the unit is stored in a cold environment, allow it to stabilize at room temperature
before powering up the unit.
d. Be sure fresh batteries are installed when beginning an extensive measurement
sequence. Periodically check the condition of your batteries by pressing BATT.
TEST. If Lo is indicated, replace your batteries.
e. When making resistance measurements at or below 10 ohms, always perform The
Low Range Calibration Procedure. Repeat the procedure to confirm the instrument’s
response.
f. During resistance measurements, stand back, away from the instrument to avoid
body capacitance or fields from effecting instrument accuracy.
g. To avoid body fields from interfering with instrument accuracy, wear a wrist strap
attached to a tested ESD ground to dissipate body charges.
2. Use only PROSTAT test leads, cables and accessories supplied with the PRS-812. Be
sure that leads are properly connected to their respective terminals as described below.
WARNING
To prevent possible electrical shock, Do Not Touch energized
circuits, leads or fixtures while grounded.
Use only pre-tested ground connections that meet local safety
standards and codes for earth grounding. Refer to National
Electrical Codes and ESD Association Standard S6.1 Grounding
for information and test procedures. Ground testing should be
conducted only by qualified personnel.
Operational Note: Low voltage batteries will affect measurement accuracy!